The present invention relates to a projector for projecting an image onto a screen and, in particular, relates to a structure for cooling an optical system incorporated in the projector.
In a conventional liquid crystal projector, an outlet fan for cooling a lamp of a lamp unit used as a light source and an inlet fan for cooling a liquid crystal light valve are separately provided. In order to suppress the rise in a lamp surface temperature, the outlet fan must run at a high speed. A lamp unit equipped with an outlet fan is disclosed in Japanese Patent Kokai Publication No. 08-114857 published on May 7, 1996, for instance.
The outlet fan running at a high speed, however, produces high noise, which has significantly degraded value that would be added to the product.
A rise in the lamp surface temperature increases the temperature of the liquid crystal light valve and other optical system components, which can degrade the component performance.
An object of the present invention is to provide a projector that can suppress rise in a lamp surface temperature and a temperature of optical system components, without increasing a running speed of an outlet fan.
According to one aspect o f the present invention, a projector comprises a lamp; a lamp box containing the lamp, an outlet fan for discharging air from the lamp box; an optical system member which receive s a light beam from the lamp and outputs an image light; an optical system box containing the optical system member; an inlet fan for blowing outside air into the optical system box; and a first ventilating duct that directs the outside air blown in by the inlet fan into the lamp box.
According to another aspect of the present invention, a projector for projecting an image displayed by the optical system members, comprises a lamp; an optical system member for receiving a light beam from the lamp; a housing containing the optical system member; an inlet fan; and a ventilating duct which lies substantially parallel to an outer wall of the housing, lets the air blown in by the inlet fan flow along the outer wall of the housing, and directs the air to a periphery of the optical system member through an opening formed in the outer wall of the housing. An inner surface of the outer wall of the ventilating duct is curved in the vicinity of a joint between the ventilating duct and an opening in the housing so that a height of the ventilating duct gradually decreases as a downstream side of the air flow approaches.
According to the present invention, the fan speed does not need to be increased, regardless of increase in lamp cooling efficiency and lamp output. In addition, the fan speed can be lowered. Accordingly, the fan noise can be reduced.
According to the present invention, the housing of the projector can be structured to serve as the whole or a part of a ventilating duct, so that the number of components can be reduced and the manufacturing costs can be suppressed.
According to the present invention, the air entering from the air inlet passes around the lamp and exits from a small opening, so that the cooling efficiency can be improved.
According to the present invention, the development of air stagnation or turbulence in the ventilating duct can be suppressed, and right locations can be appropriately cooled, so that optical elements can be efficiently cooled, suppressing the degradation of components.